Coal water slurry and preparation method thereof

Abstract

The invention discloses coal water slurry and a preparation method thereof. The coal water slurry comprises a biomass raw material, raw material coal, a coal water slurry additive and organic waste liquid. The coal water slurry is excellent in performance and completely meets the quality requirement of a coal water slurry gasification furnace on raw materials entering the furnace, the biomass raw material is used for replacing part of raw material coal, the cost of the coal water slurry is greatly reduced, meanwhile, biomass waste and organic waste liquid are fully utilized, resource utilization of waste is achieved, and good economic benefits are achieved.

Description

Technical Field

[0001] The invention relates to a water-coal slurry and a preparation method thereof, belonging to the technical field of petrochemical industry. Background Art

[0002] Coal-water slurry technology has been developed in my country for decades. With the continuous reduction of coal resources, the application of this technology has also been subject to certain restrictions. Especially in recent years, affected by the national environmental protection policies and development strategies, under the condition of insufficient fossil energy, the technological development of coal-water slurry has become an issue we have been thinking about.

[0003] At present, biomass in my country is mainly used for boiler power generation and incineration. In recent years, the biomass fuel industry in various countries around the world has grown significantly. Biomass fuel has become the main fuel in many countries. According to data, European countries produce 50% of the global biomass. In other words, 13.5 million tons of the world's 27 million tons of biomass fuel pellets are produced in European countries. Germany leads other European countries such as Sweden, Latvia and Austria. European countries mainly use biomass fuel pellets for home heating and power plants.

[0005] As a new type of pellet fuel, biomass pellets have won wide recognition for their unique advantages. Compared with traditional fuels, they not only have economic advantages but also environmental benefits, fully meeting the requirements of sustainable development. Biomass is a carbon-neutral raw material. Compared with coal, it has a high volatile content, a low ignition point, is easy to ignite, has a higher density, a higher energy density, and a significantly longer combustion duration. It can be directly used in coal-fired boilers, which is conducive to reducing coal resource consumption. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention aims to provide a water-coal slurry having excellent performance and meeting the requirements of conventional water-coal slurry production process.

[0007] In order to achieve the above technical purpose, the present invention provides a water-coal slurry, which includes biomass raw material, raw coal, water-coal slurry additives and organic waste liquid.

[0008] The present invention adopts biomass raw materials to replace part of raw coal, and at the same time mixes with water-coal slurry additives and organic waste liquid to achieve synergistic effect, so as to produce water-coal slurry fuel with better quality.

[0009] As a preferred solution, the mass of the biomass raw material does not exceed 5% of the raw coal, further preferably 2% to 5% of the raw coal, and most preferably 3% to 5% of the raw coal. The mass of the water-coal slurry additive is 2.0 to 3.0‰ of the raw coal. The mass of the organic waste liquid is 60 to 64% of the raw coal. The use of this component can obtain a water-coal slurry with excellent performance. The amount of biomass raw material added will affect the comprehensive properties of the water-coal slurry, such as viscosity, fluidity, etc., and excessive addition of biomass raw material will increase the viscosity of the water-coal slurry and deteriorate its fluidity. Therefore, controlling its addition amount within an appropriate range is conducive to improving the comprehensive performance of the water-coal slurry, while replacing part of the raw coal to achieve the effect of maximizing resource utilization.

[0010] As a preferred solution, the biomass raw material is rice straw and / or rice husk. Using rice straw and rice husk as biomass raw materials is beneficial to improving the comprehensive performance of water-coal slurry. Among them, the nitrogen, phosphorus, potassium, calcium and other elements contained in rice straw or rice husk, as well as lignin are beneficial to the surface hydrophobicity of coal slurry.

[0011] As a preferred solution, the grindability index of the biomass raw material is greater than 70. Such biomass raw materials have good grindability and are easy to crush in a coal mill.

[0012] As a preferred solution, the diameter of the biomass raw material is 6 to 10 mm, and the length is 4 to 6 times the diameter.

[0013] As a preferred solution, the Hardgrove grindability index of the raw coal is greater than 70, the volatile matter content is ≧20wt%, the ash content is 8-15wt%, the ash melting point is 1100-1420°C, and the mass ratio of silicon dioxide to aluminum oxide in the ash is 1.8-2.8:1. The total content of potassium oxide and sodium oxide in the ash of the raw coal is 1.0-3.0wt%, and the iron oxide content is less than 8. Among them, controlling the Hardgrove grindability index, volatile matter, ash content, silicon-aluminum ratio in ash and ash melting point of the raw coal within the above range can improve the carbon conversion rate, protect the water-cooled wall and prevent slag blocking in the gasifier.

[0014] As a preferred solution, the raw coal is Shenyou No. 2 coal. Shenyou No. 2 coal has the characteristics of slightly low ash melting point, low sulfur, low ash content, high iron, and relatively stable quality, and meets the requirements for the characteristics of water-coal slurry raw coal.

[0015] As a preferred solution, the pH value of the organic waste liquid is 7.0-8.0.

[0016] As a preferred solution, the organic waste liquid contains water, ammonium sulfate, caprolactam and imidazoles, and the water content of the organic waste liquid is 80-90 wt%.

[0017] As a preferred solution, the coal water slurry additive includes at least one of sodium naphthalenesulfonate formaldehyde condensate, sodium lignin sulfonate, and potassium lignin sulfonate.

[0018] As a preferred solution, the concentration of the water-coal slurry is 60wt%-64wt%, the viscosity is 700-1200mPa·s, the density is 1.15-1.30, and the pH is 7-8.

[0019] As a preferred solution, the temperature of the water-coal slurry does not exceed 70°C.

[0020] The present invention also provides a method for preparing water-coal slurry, which comprises mixing raw materials including biomass raw materials, raw coal, water-coal slurry additives and organic waste liquid to obtain the slurry.

[0021] The present invention also provides an application of water-coal slurry for preparing raw coal gas.

[0022] As a preferred solution, the process of preparing the raw coal gas is: the water-coal slurry and limestone powder are mixed and placed in a gasifier for gasification reaction to obtain the raw coal gas. The limestone powder is used as a flux. When the ash melting point of the water-coal slurry is high, adding an appropriate amount of limestone powder can help the ash melt, thereby keeping the temperature in the gasifier from being too high and increasing the fluidity of the slag in the furnace.

[0023] As a preferred solution, the amount of limestone powder added is 0.9-1.1% of the coal water slurry.

[0024] As a preferred solution, the conditions of the gasification reaction are: temperature of 1200-1500° C. and pressure of 3.0-7.0 MPa.

[0025] As a preferred embodiment, the raw coal gas includes CH4, CO, and H2.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) Biomass raw materials are used to replace part of the raw coal, which reduces the cost of water-coal slurry and the pollution caused by burning or decomposing rice straw in the field. Biomass raw materials are clean and renewable resources. On the one hand, they save energy and reduce carbon emissions. On the other hand, the resource utilization of biomass waste is green and environmentally friendly, with good economic benefits and social responsibilities.

[0028] (2) Make full use of industrial organic waste liquid and realize resource utilization of organic waste liquid;

[0029] (2) The coal water slurry has good fluidity, no precipitation is generated, meets the coal water slurry furnace entry standard, and fully meets the conventional coal water slurry production process requirements;

[0030] (3) The raw coal gas prepared by using the water-coal slurry has good quality and can be used in other downstream industries. DETAILED DESCRIPTION

[0031] The specific implementation of the invention is described in detail below in conjunction with specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0032] The organic waste liquid in the present invention is the waste liquid generated by the Beckmann rearrangement process unit in the process of producing caprolactam by the ammoximation of cyclohexanone.

[0033] The Shenyou No. 2 coal used in the present invention is purchased from Shenhua Group, and the XGC-99-II water-coal slurry additive is purchased from Yixing Xingguang Baoyi Chemical Co., Ltd.

[0034] The biomass raw material in the embodiment of the present invention is rice straw or rice husk, which is formed into particles by drying, extruding, granulating and solidifying.

[0035] Example 1

[0036] (1) adjusting the pH value of the organic waste liquid to 7.0-8.0 by passing it through an alkaline solution (such as sodium hydroxide solution);

[0037] (2) The rice straw is subjected to a dry extrusion granulation process to form a biomass raw material with a particle diameter of 6-10 mm.

[0038] (3) Shenyou No. 2 coal, other organic waste liquids, biomass raw materials and XGC-99-II coal water slurry additive are mixed according to a set ratio and then ground evenly in a coal mill to obtain coal water slurry. The raw material ratio of the coal water slurry is shown in Table 1.

[0039] Table 1 Coal-water slurry raw material ratio

[0040]

[0041] The concentration, density, viscosity and stability of the water-coal slurry were measured, as shown in Table 2. The results showed that when the amount of biomass raw material added was 8wt% (ratio 3) of the raw coal (Shenyou No. 2 coal), the apparent viscosity was above 2100mPa·s, and the fluidity was poor, which was not conducive to transportation; when the amount of biomass fuel added was 5wt% (ratio 2) of the raw coal, the viscosity of the coal slurry was in the range of 700-1200mPa·s, the fluidity was good, and no precipitation was produced. This formula achieved the maximum addition amount and can fully meet the production process requirements of water-coal slurry.

[0042] Table 2 Coal-water slurry slurry parameters

[0043]

[0044] The industrial analysis data of the water-coal slurry formed by using the ratio 2 in Table 1 are shown in Table 3 below:

[0045] Table 3 Coal-water slurry industrial analysis data

[0046]

[0047] The ash analysis data of the water-coal slurry formed by the ratio 2 in Table 1 are shown in Table 4 below:

[0048] Table 4 Coal-water slurry ash composition analysis data

[0049]

[0050] Biomass and Shenyou No. 2 coal are mixed according to ratio 2 in Table 1, and the prepared water-coal slurry is used as the raw material of the SE water-coal slurry gasifier high-temperature and high-pressure fluidized bed gasifier. The volatile matter content is greater than 20wt%, the ash content is 8-15wt%, the total content of potassium oxide and sodium oxide in the ash is less than 3.0wt%, the silicon-aluminum ratio in the ash is 1.8-2.8, the ferric oxide content in the ash is less than 8wt%, the water-coal slurry concentration is 60-64wt%, the coal slurry viscosity is 700-1200mPa·s, and all indicators meet the quality indicators of water-coal slurry entering the furnace.

[0051] The water-coal slurry obtained by mixing the mixture in the ratio 2 in Table 1 is added with 1.1wt% limestone powder relative to the water-coal slurry, and placed in a gasifier for high-temperature and high-pressure reaction, and the effective gas produced reaches more than 98%. Rice straw, rice stalks, and rice husks are biomass, which is a clean renewable energy source. The hydrogen produced is better than other hydrogen and is a clean hydrogen. Among them, the composition of the obtained raw coal gas is shown in Table 5 below.

[0052] Table 5 Composition of raw coal gas

[0053] H2S,% COS,% Ar,％ N2,％ <![CDATA[CH4,ml / m 3 ]]> CO,% CO2,% H2,％ 0.09 0.01 0.21 12.17 160 59.02 2.49 25.99

[0054] Comparative Example 1

[0055] The method of Example 1 was used to prepare water-coal slurry, except that the biomass raw material was replaced with sawdust. The proportions of the raw materials are shown in Table 6.

[0056] Comparative Example 2

[0057] The method of Example 1 was used to prepare water-coal slurry, except that the biomass raw material was replaced with corn cobs. The proportions of the raw materials are shown in Table 6.

[0058] Table 6 Slurry performance parameters of water-coal slurry formed by different biomass raw materials

[0059]

[0060] As can be seen from Table 6, when the sawdust is added in an amount of 2wt% of the raw coal, the apparent viscosity of the water-coal slurry formed is 1260m·Pa.s, the liquid is relatively viscous, and the surface of the fluid is not very smooth, which is not conducive to pumping. When the corn cob is added in an amount of 2wt% of the raw coal, the apparent viscosity of the water-coal slurry formed is 1220m·Pa.s, and the surface of the fluid is not smooth. Compared with sawdust and corn cobs, the water-coal slurry formed by the same amount of rice straw added in the present invention has excellent performance, low viscosity, good fluidity, no precipitation, and fully meets the requirements of the water-coal slurry production process. Even when the amount of addition is increased to 5wt% of the raw coal (Example 1 Ratio 2), the water-coal slurry formed still shows good slurrying performance. It can be seen that the rice straw biomass raw material has better compatibility with the raw coal. Compared with other biomass raw materials, it can make the water-coal slurry have better performance and is more suitable for replacing part of the raw coal to reduce energy consumption.

Claims

1. A coal-water slurry, characterized in that: Including biomass raw materials, raw coal, water-coal slurry additives and organic waste liquid.

2. A coal water slurry according to claim 1, characterized in that: The mass of the biomass raw material does not exceed 5% of the raw coal; The mass of the water-coal slurry additive is 2.0-3.0‰ of the raw coal; The mass of the organic waste liquid is 60-64% of the raw coal.

3. A coal water slurry according to claim 1 or 2, characterized in that: The biomass raw material is rice straw and / or rice husk.

4. A coal-water slurry according to claim 1 or 2, characterized in that: The biomass raw material has a diameter of 6 to 10 mm and a length of 4 to 6 times the diameter.

5. The coal water slurry according to claim 1, characterized in that: The raw coal has a Hardgrove index greater than 70, a volatile matter content of ≧20wt%, an ash content of 8-15wt%, an ash melting point of 1100-1420°C, and a mass ratio of silicon dioxide to aluminum oxide in the ash of 1.8-2.8:

1.

6. The coal water slurry according to claim 1, characterized in that: The organic waste liquid contains water, ammonium sulfate, caprolactam and imidazole substances; the pH value of the organic waste liquid is 7.0-8.

0.

7. A coal water slurry according to claim 1, 5 or 6, characterized in that: The coal water slurry additive includes at least one of sodium naphthalene sulfonate formaldehyde condensate, sodium lignin sulfonate and potassium lignin sulfonate.

8. The coal water slurry according to claim 1, characterized in that: The concentration of the water-coal slurry is 60wt%-64wt%, the viscosity is 700-1200mPa·s, the density is 1.15-1.30, and the pH is 7-8.

9. The method for preparing a coal water slurry according to claims 1 to 8, characterized in that: The raw materials including biomass raw materials, raw coal, water-coal slurry additives and organic waste liquid are mixed to obtain the product.

10. The use of a coal water slurry according to claim 1, characterized in that: Used to prepare raw coal gas.

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